Support integers exceeding Number.MAX_SAFE_INTEGER

[tommy-ish]

I would like openapi-typescript and openapi-fetch to support integers exceeding Number.MAX_SAFE_INTEGER.

For example, openapi-typescript turns following schema into bigint type.

type: integer
format: int64

openapi-fetch post following object into following JSON.

{
  foo: 9007199254740992n
}

{
  "foo": 9007199254740992
}

openapi-fetch parse following JSON into following object.

{
  "foo": 9007199254740992
}

{
  foo: 9007199254740992n
}

[drwpow]

This is a common sticking point with many fetch APIs. Unfortunately it balloons into having to replace the optimized, extremely-fast response.json() utility (that uses JS’ built-in JSON parser) with something custom, which would slow down everyone’s code (there’s no way to conditionally do it, either, because scanning for the presence of BigInt slows everything down).

Is there an existing JSON parser that support this? Any prior art of other fetch libraries that support this? Any language spec proposals that may unblock this?